Patent Document 1 (identified below) discloses a wireless communication device (RFID (“Radio-Frequency Identification”) tag) in which a wireless IC element (RFIC (“Radio-Frequency Integrated Circuit”) chip) and a conductor pattern connected thereto are protected by a protective case made of a resin. The RFIC chip and the conductor pattern are disposed on a surface of a dielectric block that is housed in the protective case. The conductor pattern includes a radiation conductor disposed on a first principal surface of the dielectric block and connected to one terminal of the RFIC chip, a ground conductor disposed on a second principal surface opposite to the first principal surface and connected to the other terminal of the RFIC chip, and a short-circuit conductor connecting the radiation conductor and the ground conductor. By affixing the RFID tag to a metal surface of an article such that the ground conductor faces the metal surface (by capacitively coupling the ground conductor and the metal surface through the protective case), the RFID tag can perform wireless communication even when attached to the metal surface.
Patent Document 1: Japanese Laid-Open Patent Publication No. 2012-253700.
However, the RFID tag described in Patent Document 1 requires many constituent elements and has a complicated structure that increases dimensional variations of members and electric characteristic variations due to temperature characteristics, so that manufacturing costs become high. For example, a dielectric block is required for holding an RFIC chip, a radiation conductor, etc., and if the thermal expansion characteristic of the dielectric block is different from the thermal expansion characteristic of a supporting film of the conductor pattern, the electric characteristics of the RFID tag deteriorate due to temperature cycles. Moreover, since it is necessary to respectively dispose the RFIC chip, the radiation conductor, and the ground conductor on different surfaces of the dielectric block, the supporting film of the conductor pattern must be affixed in a wrapping manner, which makes it difficult to ensure positioning accuracy, so that electric characteristic variations due to processing accuracy increase.